This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-266950, filed Sep. 21, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to an image forming apparatus and particularly to an image forming apparatus which forms an image by a wet developing method with use of a liquid developer in which toner is dispersed in a solvent.
An image forming apparatus using a liquid developer attracts attention again as a technique which matches with high speed and high image quality and can provide an image with high image quality owing to toner of fine grains. This apparatus is excellent in gradient reproductivity and can provide an image equal to printing. The softening point of the toner is low and an advantage is obtained in that images can be easily fixed. However, since the developer is a liquid composed of toner grains and a carrier liquid, further improvements are required for the supply method thereof and the method of removing an excessive developing liquid (carrier liquid) remaining on a photosensitive member. In the present situation, a satisfactory image forming apparatus has not yet been obtained with respect to the developing device, transfer device, and cleaning devices for respective parts.
U.S. Pat. No. 5,576,815 discloses a wet electrophotographic color image forming apparatus.
FIG. 11 is a view schematically showing the wet electrophotographic color image forming apparatus described in an embodiment of the above-mentioned patent.
In the patent according to the invention in the patent, there is a description that the image forming apparatus includes xe2x80x9ca plurality of developing sections 12, 14, 16, and 18 arranged along a route of a photosensitive member, and in FIG. 11, the system 10 is constructed so that a multi-color image can be formed by one single path of a photosensitive member 20 provided therein. If this kind of single bus system 10 is adopted, a multi-color image can be formed at a very high speed.xe2x80x9d
Also, the patent describes that xe2x80x9cthe image forming apparatus according to the above-described invention can be applied to a single-color liquid developing system and a multi-color/multi-path liquid developing system, although the image system 10 is shown as a multi-color/single-path step in FIG. 11.xe2x80x9d
Further, there is a description saying the xe2x80x9capplicability to a system in which the photosensitive member is a belt, drum, or sheet-like onexe2x80x9d. However, the embodiment only shows a belt-like photosensitive member but does not at all describe merits obtained in case where the photosensitive member has a drum-like shape. It does not describe originality or inventivity which should be required because the photosensitive member is a drum-like member, or improvements thereof. Thus, the patent merely suggests possibility of a drum-like photosensitive member.
Actually, in case of a drum-like photosensitive member, further originality, inventivity, and improvements are required.
On the other hand, the present invention provides a wet electrophotographic color image forming apparatus which realizes a multi-color/single-path step in case of using a drum-like photosensitive member (including a drum with a sheet wound thereon) and provides a wet electrophotographic color image forming apparatus which overcomes all the conventional problems.
The present invention has an object of providing a color image forming apparatus according a liquid developing method and a developing liquid supply unit, which uses a drum-like photosensitive member and are capable of forming multi-color images at a high speed.
The present invention has been made on the basis of the problems described above and provides a developing liquid supply unit which has a casing for containing a developing liquid and is detachably attached to an image forming apparatus, comprising: a driven member for receiving a drive force from outside; a discharging section for discharging the developing liquid from the casing to the outside; a receiving section for receiving the developing liquid from the outside into the casing; and a developing liquid transfer mechanism for supplying the developing liquid in the casing, to a developing device in the image forming apparatus, through the discharging section, based on the drive force to the driven section, and for further returning the developing liquid from the developing device into the casing through the receiving section, in a situation that the developing liquid transfer mechanism is attached to the image forming apparatus.
Also, the present invention provides an image forming apparatus comprising: a latent image forming mechanism for forming an electrostatic latent image on a photosensitive member; a developing device for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed, thereby to develop the latent image; a removing device for removing an excessive portion of the developing liquid supplied by the developing device, the excessive portion of the developing liquid remaining on the photosensitive member after development; and a returning mechanism for returning the excessive portion of the developing liquid, which is removed by the removing device, into a casing of a developing liquid supply unit for supplying the developing liquid to the developing device.
Also, the present invention provides an image forming apparatus comprising: a plurality of latent image forming devices provided along an arc-like surface of a photosensitive member, for forming an electrostatic latent image on the surface of the photosensitive member; and a plurality of developing mechanisms for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed, thereby to develop the latent image, wherein the latent image forming devices includes a plurality of light sources each has a laser device, a single deflection device for deflecting a plurality of beams respectively generated from the laser sources, and an imaging lens for providing the plurality of beams deflected by the deflection device with a predetermined characteristic, thereby to form an image on the photosensitive member.
Also, the present invention provides an image forming apparatus comprising: a plurality of latent image forming devices provided along an arc-like surface of a photosensitive member, for forming an electrostatic latent image on the surface of the photosensitive member; a plurality of developing mechanisms provided along the arc-like surface of the photosensitive member, for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed, thereby to develop the latent image; and a plurality of hold member for holding the developing mechanisms such that lowermost parts of developing rollers, levels of the developing liquid, and end parts of openings are arranged in this order from a lower side in a gravitational direction, respectively.
Also, the present invention provides an image forming apparatus comprising: a plurality of charging device provided along an arc-like surface of a photosensitive member, for charging the surface of the photosensitive member; a plurality of latent image forming mechanisms for forming electrostatic latent images on the surface of the photosensitive member charged by the charging device, respectively; and a plurality of developing devices for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent images are formed by the latent image forming mechanisms, thereby to develop the latent images, respectively.
Also, the present invention provides an image forming apparatus comprising: a plurality of latent image forming mechanisms provided along an arc-like surface of a photosensitive member, for forming at least one electrostatic latent image on the surface of the photosensitive member; a plurality of developing devices for supplying a developing liquid containing at least toner and a carrier liquid, to the electrostatic latent image formed on the surface of the photosensitive member, thereby to develop the latent images; and a plurality of developing liquid removing mechanisms respectively provided for the developing devices, for removing an excessive portion of the developing liquid from the surface of the photosensitive member supplied with the developing liquid.
Also, the present invention provides an image forming apparatus comprising: a latent image forming mechanism for forming an electrostatic latent image on a photosensitive member; a developing device for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed by the latent image forming mechanism, thereby to develop the latent image; and a removing device for removing an excessive portion of the developing liquid supplied to the photosensitive member by the developing device, the excessive portion of the developing liquid being on the photosensitive member, wherein the removing device includes a nozzle having a top end provided near the surface of the photosensitive member, and having a through-hole, a suction device for suctioning the developing liquid through the through-hole of the nozzle, and a positioning mechanism for setting a predetermined distance between the top end of the nozzle and the photosensitive member.
Also, the present invention provides an image forming apparatus comprising: a latent image forming mechanism for forming an electrostatic latent image on a photosensitive member; a developing device for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed by the latent image forming mechanism, thereby to develop the latent image; and a removing device for removing an excessive portion of the developing liquid supplied to the photosensitive member by the developing device, the excessive portion of the developing liquid being on the photosensitive member, wherein the removing device includes a suction device for suctioning air, a pipe member for connecting the suction device with the suction nozzle near the photosensitive member, and a filter member provided in a middle of the pipe member, for separating the carrier liquid from the air suctioned.
Also, the present invention provides an image forming apparatus comprising: a photosensitive member; and a wet color image forming unit of an integrated type including a plurality of developing rollers, a plurality of removing devices for removing an excessive portion of a developing liquid on the photosensitive member, and a plurality of windows for passing a light beam from an exposure device, for forming an electrostatic latent image on the photosensitive member.
Also, the present invention provides an image forming apparatus comprising: a latent image forming mechanism for forming an electrostatic latent image on a photosensitive member; a developing device for developing the electrostatic latent image by supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the electrostatic latent image is formed by the latent image forming mechanism, thereby to form a toner image; an offset roller provided in contact with the photosensitive member and rotated in synchronization with rotation of the photosensitive member, so that the toner image formed by the developing device is transferred onto the offset roller; and a cleaning mechanism for removing the toner from the offset roller, wherein during cleaning, the offset roller is rotated by one turn or more in contact with the offset roller.
Also, the present invention provides an image forming apparatus comprising: a latent image forming mechanism for forming an electrostatic latent image on a photosensitive member; a developing device for supplying a developing liquid containing at least toner and a carrier liquid, to the photosensitive member on which the latent image is formed by the latent image forming mechanism, thereby to develop the electrostatic latent image; a removing device for removing an excessive portion of the developing liquid supplied by the developing device, the excessive portion of the developing liquid remaining on the photosensitive member; and a developing liquid collecting mechanism connected with the developing liquid removing device, for collecting the developing liquid by suctioning the liquid, wherein an exhaust gas generated by the developing liquid collecting mechanism is circulated inside the image forming apparatus.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.